Recognition of natural silk fibers, dyes and metal threads of historical Romanian textile fragments using the multi-analytical techniques approach

A multi-analytical technique approach involving the combined use of micro-invasive and nondestructive techniques was used to identify the type of fiber, mordant and natural dye constituents for eight historical textiles fragments from the 17th–18th centuries, found in monasteries in Northern Romania. The analysis was performed using optical microscopy (OM), scanning electron microscopy with an energy-dispersive X-ray detector (SEM-EDX), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and high-performance liquid chromatography (HPLC). HPLC could determine two flavonol-based structure yellow dyes (possibly weld and Persian berries), one naphthoquinone-based structure brown dye (juglone-walnut) and five samples composed of anthraquinone-based structure red dyes (two fragments contain kermes, one cochineal, one lac and one madder). Elemental analysis using EDX was utilized to identify the possible using of alum as a mordant and the use of metallic threads (pure silver and gilt threads). OM and SEM techniques identified the fiber type and the existence of metal threads, while ATR-FTIR analysis could provide an initial idea about the functional groups of the textile components for the fiber structure substrates.